OnGuard Mastiff Quad Chain Lock

If you have ever had a bike stolen you know how frustrating it can be. Around the world, and particularly in the United States, bike theft is on the rise. Criminals just don’t seem to be deterred by the thought of a misdemeanor charge or fine for stealing a bike – especially drug addicts who need that next fix to keep from going into withdrawal.

Luckily, there are a few companies out there that make amazing locks that will prevent even the most determined bike thief from taking off on your bike. One of my favorites if this OnGuard Mastiff chain lock, a bike lock that will stand up to crowbars, bolt cutters and a whole lot more. It has been one of the best locks that I have ever owned.


Introduction To The OnGuard Mastiff Quad Chain Lock

This lock is named Mastiff, which makes you think of a guard dog that is going to keep your bike safe and the name is pretty apt. This is a really great lock with a big resemblance to one of the top locks from Kryptonite, which is one of the most recognizable brands on the market.

This is a chain lock made to resist everything from sheer force of leverage from a crowbar to the sharp teeth of a bolt cutter. In addition, the fabric sleeve protects your bike from scratching and the disc lock that is embedded into the circular shaft makes it almost impossible to pick or drill when the lock is closed.

With titanium reinforced steel square chain links and a reinforced outer layer over the locking cylinders this lock is made to keep your bike safe in high-risk areas. While you still shouldn’t take chances, this lock will protect your bike no matter where you have to lock it up.



My Results

My results with this lock have been nothing short of amazing. If you want a lock that is going to protect your bike from just about everything, but is still light enough to carry around without having too much weight on your bike or in your saddlebags, this is the perfect lock. Plus, the locking mechanism is smooth – the knife through butter cliché comes to mind.


The bottom line is that I still have my bike months after getting this lock and that is saying a lot because I ride my bike everywhere. There have been plenty of opportunities for a thief to steal my bike and so far all of them have been thwarted.

What Others Say

There are a lot of people who really love this lock. For example, Brian Lafond rated this lock five stars on Amazon and commented on how solid and tough this chain lock was. His opinion was, that even with an angle grinder, it would take a thief a great deal of time to get through it, not to mention withstanding bolt cutters and simple brute force crowbar attacks.

Other people also lauded this lock for how high-quality it was and how it protected their bikes. Some people were protecting bicycles ranging in value from $500 to $1500 but other people were protecting a whole lot more, like e-bikes or moped that cost several thousand dollars. They were all happy with the job that the Mastiff did.

Insider Information

One thing that you should be aware of is how heavy this lock is. It isn’t a problem, although for racing bikes, you may have a little bit of problem reaching the speed you want with this much weight on your bike. For everyone else, you can easily carry it on your bike, but just be aware of how much heft this has. The lock is also quite a bit bigger than it looks in the picture. It says 2.4 pounds on the product description but it has to be at least twice that.


Buying Advice

When it comes to buying advice there are two bits of wisdom that I want to impart. First, there are different sizes available and while this should be your main lock – the one that you put through the most expensive part of your bike like the frame – you can get the smaller ones to use on the tires and you will be able to protect your bike even further.

The second thing that I would recommend is that you go ahead and sign up for Amazon Prime. It’s ten bucks a month and you will save that with this purchase, especially if you buy more than one. This product comes with free shipping with an Amazon Prime membership and it’s really fast.


So, this lock gives you massive protection against theft because of the way that it is constructed. It has square steel links reinforced with titanium to make it even stronger.

It has a protective sleeve to keep it from scratching your bike and even the cylinders that contain the locks have reinforced sleeves for extra protection. The lock is pick-proof and drill-proof and this is probably the last lock that you will ever have to buy.

My Verdict

Obviously, since I use this lock myself I heartily recommend it. I didn’t get more than one but I’ve been thinking about grabbing a couple more of the smaller ones. I don’t necessarily think that my bike is going to get stolen with the Mastiff on it, but a couple smaller ones would be nice to have.

Even if you only get the main lock, I definitely recommend it. It is the best lock that I have ever owned.


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Protect Your Bike From Theft!

Download our FREE eBook guide and learn which bike locks are virtually indestructible and will keep your bike safe.

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